SPITFIRE CHANNEL REALIGNMENT IMPACT ASSESSMENT: EPBC ACT REQUIREMENTS

August 2005

Prepared by WBM Oceanics Australia

The Port of Brisbane Corporation proposes to secure long-term sand resources from Moreton Bay to support on-going development of Port-related infrastructure at the Port of Brisbane. It is proposed that this resource be generated as a result of shipping channel improvements via the development of a new section of the Spitfire Channel. The project is located in the Northern Delta entrance to Moreton Bay approximately 30km north of the Port of Brisbane, and some 8km from Bribie Island to the west and a similar distance Moreton Island to the east.

A significant body of investigative works has been undertaken into the impacts of large-scale sand extraction in Moreton Bay via the Moreton Bay Sand Extraction Study (MBSES), led by the Queensland Environmental Protection Agency and supported by stakeholders including the Port of Brisbane Corporation. The MBSES included extraction scenarios within the Spitfire Channel area.

These studies found that direct and indirect impacts associated with the long-term removal of shallow sand banks, including changes to wave conditions, tidal currents and potential alterations to ecological communities, are predicted to be indiscernible. This led to a Queensland Government policy to support sand extraction from Moreton Bay to address the needs of large-scale development projects and the construction sector.

Subsequently, the Corporation has commissioned WBM to provide advice with respect to the specific Spitfire Channel extraction design as presently proposed. This involves extraction of 15Mm3 of sand to develop a shipping channel 7.8 km in length, to a maximum depth of -16.5mLAT over a 15-year planning horizon. The channel alignment will reduce the length of the Spitfire Channel by l km (11%) and remove three sharp turns within the existing channel, thereby improving shipping efficiency and safety. The focus of this study was to investigate the potential for the proposed sand extraction to impact the regional hydrodynamic and morphological process of Moreton Bay.

The study area is part of the much larger Northern Moreton Bay delta system, containing approximately 4 billion m3 of sand. The vast scale of the delta system is such that contemporary changes due to natural processes are relatively slow and indiscernible. Even the proposed channel dredging is of a relatively small scale in the context of the size of the overall delta system.

The sand banks of the Northern Delta are continuing to receive an ongoing supply of sand and are continuing to evolve their shape over the long term under the influences of waves and currents. There is no evidence of contemporary supply of sand from the North Banks directly to the shoreline of either Bribie Island or Caloundra, being separated from those areas by naturally deep water across which sand transport by wave action is zero or negligible.

The results of the modelling undertaken for this study were consistent with the findings of the MBSES and indicate that the impact of the works would be restricted to the project area and immediate surrounds, with minor local redistribution of currents and wave action. The proposed works have no potential to impact the shorelines of the adjacent Ramsar-listed areas of Moreton Bay, either directly or though changes to currents and/or wave climates, and consequently sand supply. Hence, the project would not trigger a controlled action under the Environment Protection and Biodiversity Conservation Act 1999 in terms of the hydrological impacts significantly altering the ecological character of a matter of National Environmental Significance.